This invention relates to a control center having a plurality of plug-in type control units stacked in multiple layers therein.
Control centers are frequently of the back-to-back type including a plurality of control units housed on each of the front and rear sides therein. Conventional control centers of the type referred to have comprised a vertical bus compartment disposed in the central portion thereof in which a plurality of vertical buses are disposed, a pair of unit compartments disposed therein with the vertical bus compartments therebetween and the compartments on the front and the rear thereof, a plurality of control units housed in each of the unit compartments and stacked in multiple layers, the control units being supplied with electric powers through the vertical buses respectively, and a vertical wiring compartment disposed adjacent to the lateral side of each unit compartment. Further a cabinet formed of the compartments as described above has included a horizontal bus compartment and a cable entrance compartment disposed on the upper and lower surfaces thereof respectively.
There are already known control units of the type adapted to be housed in each of unit rooms of the unit compartments. One such control unit has comprised a U-shaped unit casing having a pair of opposite lateral plates and a rear plate connected to one another, a front crossarm for connecting front upper corners of the lateral plates, a mounting plate fixed to the inner surface of one of the plates, electric equipment such as a circuit breaker, an electromagnetic switch, a terminal board etc. disposed on the mounting plate and a plug-in type connector disposed on the rear plate to connect the electric equipment to associated vertical buses respectively.
When the control unit is drawn out from an associated one of the unit rooms or when an empty unit room has its door put in the open position, the associated vertical buses are exposed resulting in a danger. In order to avoid this danger, it has previously been the practice to interpose a barrier formed of a synthetic resinous material between the rear surface of each unit casing and the vertical buses. Alternatively, the vertical buses as a whole can be sandwiched between a pair of synthetic resinous covers which also serve to support the vertical buses. In either case it has been required to use expensive resinous products having a high quality resulting in bad economy.
Also the control unit as described above has included a plurality of cables extending into the unit casing through the lower end of one of the lateral plates to the electromagnetic switch and terminal board. In order to prevent the upwardly extending end portions of the cables from being caught by the rear plate of the unit casing upon drawing the control unit out of the associated unit room, the rear plate has been provided at the lower end with a notch through which the cables extend out from the unit casing. However the dimension of the notch has been frequently insufficient because of the size and number of the cables. Thus the cables may be damaged.
In addition, in the control center as described above the cabinet is incapable of being provided on each of the front and rear faces thereof with a reinforcing crossarm or crossarms because such a crossarm or crossarms interferes or interfere with the insertion and removal of the control units into and from the cabinet. This has resulted in the disadvantage that the cabinet is low in lateral strength.
Accordingly it is an object of the present invention to provide a new and improved control center including means for preventing danger due to vertical buses therein without using expensive synthetic resinous products, and having a high lateral strength and from which control units housed in the control center can easily be drawn out.